In producing gas wells, or oil wells having an appreciable gas/oil ratio, the gas is usually laden with water. The water must be removed from the gas prior to the entrance of the gas into the sales gas line.
The water is usually extracted from the gas by means of a glycol dehydrator system wherein a contactor or scrubber admits the flow of dry glycol and gas in countercurrent flow relationship therethrough, so that the water is absorbed or scrubbed from the gas. The wet glycol is subsequently distilled; thereby removing most of the water therefrom, and the treated glycol is then recycled to the contactor.
There are instances where the water which is intrained within the gas has an appreciable amount of salts, such as NaCl, dissolved therein. The salt remains suspended in solution as the wet glycol is pumped to the distillation unit, and upon evaporation of water therefrom, the composition of the equilibrium system is changed in a direction whereby the salt component thereof eventually accumulates to become a super-saturated solution. The concentration of the salt component progressively increases until salt crystallization occurs within the system flow lines. This action causes deposition of the crystalline salt within the glycol pump, as well as within some of the colder parts of the system. The deposition of salt within the pump reduces its life and requires periodic maintenance and repairs thereof, which also necessitates reduced well production.
Accordingly, it is desirable to be able to desalt the dry glycol at a location upstream of the pump so that the salt is precipitated or crystallized therefrom at a predetermined location where it can be easily removed from the system.